A survey was undertaken in the Te Waiiti Stream, Bay of Plenty, in summer 2002/2003, to identify blue duck (Hymenolaimus malacorhynchos) roost habitat. Thirty-six roosts were identified along 18.5 km of stream channel, averaging three roosts per blue duck pair. Stable undercut banks were most commonly used as roost sites (42%), followed by log jams along stream banks (25%). Large woody debris (LWD) was a component of 50% of the roost sites, and there was a positive relationship between LWD loadings in the stream channel and number of LWD roosts. All roosts provided overhead and lateral cover, most likely an adaptive response to current and historic avian predators, and all were located at the water’s edge. The location and composition of roosts provided easy access to the stream channel, discrete cover for rearing juveniles and for moulting, and daytime shelter. There were indications that channel morphology characteristics in the lower section of the survey reach may be limiting roost habitat availability and blue duck occupancy. Suitable roost habitat is a year-round requirement for blue duck and should be considered when evaluating their habitat.
We describe and name a new subspecies of fulmar prion as Pachyptila crassirostris flemingi. This little-known seabird has less than 1,000 pairs breeding at the Auckland Islands and 1,000-10,000 pairs breeding on Heard Island. It is probably largely sedentary around these islands in winter, with possible stragglers reaching mainland New Zealand and Tasmania.
The Antipodean wandering albatross (Diomedea antipodensis) is endemic to Antipodes Island in the New Zealand subantarctic. A programme of regular census and population study was initiated on Antipodes Island in 1994 to determine the status of the species. This paper reports on field work carried out every summer from 1994 to 2005. Aspects of breeding biology are described and compared with those of other species of wandering albatross, particularly the closely related Gibson’s wandering albatross (D. gibsoni) on Adams Island. Average annual survival over 10 years was 0.957. Productivity was measured over 11 years and averaged 0.74 chicks per nesting pair. Survivorship was similar to that in the increasing Diomedea exulans population on Crozet Island, and productivity higher than recorded in all other wandering albatross populations. Between 1994 and 1997, the average annual number of pairs nesting on Antipodes Island was 5136. There is evidence of population decline during the 1970s but numbers are now increasing.
A previously unknown population of Coenocorypha snipe was discovered on Jacquemart Island, a rat-free 19 ha islet adjacent to Campbell Island in the New Zealand subantarctic, on 9 November 1997. This was the first evidence of Coenocorypha snipe occurring in the Campbell Island group, which is believed to have been infested by Norway rats (Rattus norvegicus) before the first naturalists visited in 1840. Rats were eradicated from 11,268 ha Campbell Island by the New Zealand Department of Conservation in July 2001. Two snipe were seen, and one caught, on Campbell Island adjacent to Jacquemart Island on 10 March 2005. The bird caught was a fully-feathered chick, indicating successful breeding on Campbell Island. The Campbell Island snipe remains undescribed and critically endangered.
Counts, mark-recapture estimates of abundance, and simulations were used to assess the population trends of Antipodean wandering albatross (Diomedea antipodensis) and Gibson’s wandering albatross (D. gibsoni). Estimates of population size based on mark-recapture analysis had much greater power to detect trends than did annual counts of nests. In fact, nest counts were so variable that significant trends would only be detected when populations had already changed by more than 25%. Population simulation models were constructed using survival and productivity data from the two species, and recruitment data from closely related species. The simulation models were sensitive to variation in recruitment data and suggested that the recruitment of Gibson’s wandering albatrosses is significantly lower than that of Antipodean wandering albatrosses. The sensitivity of the models to variation in the surrogate data compromises the usefulness of such models as predictive tools. After large, probably fisheries-induced declines during the 1970s and 1980s, Antipodean wandering albatross populations are now increasing at about 3.1% per annum, while Gibson’s wandering albatross populations are static.
New Zealand bellbirds (Anthornis melanura) disappeared suddenly from the northern New Zealand mainland and several large northern islands in the late 19th century. During the past 75 years, several unsuccessful attempts were made to reintroduce them. Between 1988 and 1991, four translocations (111 birds) were made to Waiheke Island near Auckland, sourced from Kaingaroa (21 birds) and Cuvier Island (90 birds). The birds were conspicuous immediately after release but became progressively less visible within six months and the translocations failed. While the cause(s) of failure are unknown, predation by mammalian predators, especially ship rats (Rattus rattus) is likely to have been a critical factor. Other possible reasons for failure of bellbird translocations are discussed, along with the reasons why original bellbird populations disappeared from northern New Zealand and subsequently failed to re-establish.
We observed black and white-plumaged storm petrels on 27 seabird-watching trips to the outer Hauraki Gulf, New Zealand, November 2003 – June 2005. We studied their plumage characteristics, behaviour and seasonal occurrence: the birds had common plumage characteristics and sightings of them were concentrated in the outer Hauraki Gulf from October to March and further offshore in April-May. Their presence in the Hauraki Gulf coincided with summer breeding of other seabirds, in particular white-faced storm petrels (Pelagodroma marina). Their pattern of occurrence off northern New Zealand suggests the birds may be breeding in the Hauraki Gulf; the Mokohinau Islands, rid of rats (Rattus exulans) 15 years ago, is a potential breeding site In our view these black and white storm petrels do not conform to descriptions of any extant species known from New Zealand waters, and, consequently, we speculate that our observations may have been of New Zealand storm petrels (Pealeornis maoriana Mathews 1932), a species known from only three specimens collected in the 19th century.
Recaptures of banded birds, and call counts, indicate a population of great spotted kiwi (Apteryx haastii) near Saxon Hut, Heaphy Track, in Kahurangi National Park has remained stable between 1987 and 2004. The number and the locations of occupied territories have changed little. Although few juveniles were encountered during searches with dogs, at least 10 of 22 territorial adults present in 1987 were replaced by a total of 12 birds over 17 years implying that recruitment kept pace with the annual adult mortality of about 4%. We suggest that the incidence of the main predators of kiwi (stoats, ferrets, cats and dogs) was low in this very wet area (rainfall >5500 mm/ year). Our findings support the current ‘Vulnerable’ conservation threat ranking for the species.
We experimentally evaluated the food hoarding behaviour of North Island robins (Petroica australis longipes) at Karori Wildlife Sanctuary, Wellington. Mealworms were offered to free-ranging pairs of male and female robins to evaluate whether their food hoarding behaviour was similar to previous observations of South Island robins. We also tested theoretical predictions derived in the Northern Hemisphere, which argue that competitively subordinate birds should hoard more food than dominant birds. Results showed that the food hoarding behaviour of North Island robins was similar to South Island robins, except that North Island robins repeatedly used the same cache sites, which is rare in South Island robins. Data did not support the prediction that competitively subordinate birds hoard more food than dominant birds. Males acquired most of the mealworms offered to birds during trials, and won nearly all aggressive interactions observed between sexes. Therefore, males appeared to be competitively dominant to females in winter. However, males stored over five times as many mealworms as females, which is opposite to theoretical predictions. We interpret the reluctance of females to cache food as a strategy to avoid food loss to competitively dominant males.